I am both a new S70D owner and a new poster. I've searched here for info on this issue, but no luck. I live in North San Diego County and am at the mercies of San Diego Gas & Electric. About a year ago, I installed a solar array on my roof which was sized to cover my electrical use history. It is a 3.9kw array , which over the past year averaged 577kwh per month with a variation of 420kwh in the winter to 700kwh in the summer months. With the exception of two hot months last fall, when I was forced to run air conditioning, the array has nicely covered all our needs, and allowed us to send power back to the grid. I bought the car at the end of December, and am wondering how best to charge it (I do have a 240v/50a circuit). We don't drive it all that much, maybe about 15-20 miles per day on average, which includes several trips to Palm Desert where I can use a Supercharger. Questions: a. Should I plug it in after every use, even if it's only a few miles? Our current mode is to charge every 3 days or so. i.e., frequent small charges vs. periodic larger charges? b. Is it better to charge when the sun is charging the solar array, or at night and taking power from the grid? Or, does it not matter? We do not have time of use rates, currently. My grid rate is about 17.5 cents/kwh. c. Is it cost effective to increase the capacity of the solar array to cover the car needs. This is feasible, but I suspect not worthwhile. d. Is more info needed?